Back to EveryPatent.com
| United States Patent |
6,093,854
|
|
Su
, et al.
|
July 25, 2000
|
Process for preparing alkanolamines from polyolefin epoxides
Abstract
Disclosed herein is a process for producing alkanolamines from the reaction
between a polyolefin epoxide and an organic amino compound under
conditions of elevated temperature and pressure, in the presence of a
catalytic amount of an alcohol. Higher reaction rates for alkanolamine
production than provided in the prior art may be achieved by use of a
process according to the invention. Alkanolamines having various levels of
nitrogen may be produced by the invention.
| Inventors:
|
Su; Wei-Yang (Austin, TX);
Larkin; John Michael (Austin, TX)
|
| Assignee:
|
Huntsman Petrochemical Corporation (Austin, TX)
|
| Appl. No.:
|
418686 |
| Filed:
|
October 14, 1999 |
| Current U.S. Class: |
564/477 |
| Intern'l Class: |
C07C 213/00 |
| Field of Search: |
564/477
|
References Cited
U.S. Patent Documents
| 4342840 | Aug., 1982 | Kozawa et al. | 521/137.
|
| 4566963 | Jan., 1986 | Ott et al. | 204/181.
|
| 4612335 | Sep., 1986 | Cuscurida et al. | 521/167.
|
Primary Examiner: Barts; Samuel
Attorney, Agent or Firm: Stolle; Russell R., Brown; Ron D., Whewell; Christopher J.
Parent Case Text
This Application claims the benefit of U.S. Provisional Application Ser.
No. 60/107,520 filed Nov. 7, 1998, which was pending at the time this
Application was filed.
Claims
We claim:
1. An alcohol-catalyzed process for forming an alkanolamine from an epoxide
and an amino compound which comprises:
a) providing an epoxide;
b) providing an amino compound;
c) providing an effective catalytic amount of an alcohol;
d) causing the amino compound to contact the epoxide in the presence of
said catalytic amount of an alcohol under conditions of elevated
temperature and pressure sufficient to cause a reaction resulting in the
formation of an alkanolamine.
2. The process according to claim 1 wherein said conditions include
elevation of the temperature at which the reaction takes place to a
temperature in the range of about 50 degrees centigrade to 300 degrees
centigrade, including every degree therebetween.
3. The process according to claim 1 wherein said conditions include
elevation of the temperature at which the reaction takes place to a
temperature in the range of about 150 degrees centigrade to 250 degrees
centigrade, including every degree therebetween.
4. The process according to claim 1 wherein said conditions include
elevation of the temperature at which the reaction takes place to a
temperature in the range of 180 degrees centigrade to 230 degrees
centigrade, including every degree therebetween.
5. The process according to claim 1 wherein said epoxide is an epoxide of a
polyolefin.
6. The process according to claim 1 wherein said polyolefin is derived from
an olefinic monomer having a carbon atom content of between one and twelve
carbon atoms per molecule, including every integral number of carbon atoms
therebetween, and whether straight-chain, branched, or cyclic.
7. The process according to claim 5 wherein said epoxide has a molecular
weight in the range of 170 to 5000 and every molecular weight
therebetween.
8. The process according to claim 5 wherein said epoxide has a molecular
weight in the range of 500 to 2500, and every molecular weight
therebetween.
9. The process according to claim 5 wherein said epoxide has a molecular
weight in the range of 750 to 1800 and every molecular weight
therebetween.
10. The process according to claim 1 wherein said alcohol has fewer than
ten (10) carbon atoms per molecule, and said epoxide is insoluble in said
alcohol.
11. The process according to claim 1 wherein the pressure is in the range
of: atmospheric pressure to 5000 psig, including every integer psig
therebetween.
12. The process according to claim 1 wherein the pressure is in the range
of: 1000 to 3000 psig and every degree of psig therebetween.
13. The process according to claim 1 wherein the pressure is in the range
of 1500 to 2500 psig and every degree of psig therebetween.
14. The process according to claim 1 wherein said alcohol is selected from
alcohols having between 1 and 20 carbon atoms per molecule.
15. The process according to claim 1 wherein said alcohol is selected from
alcohols having between 1 and 10 carbon atoms per molecule.
16. The process according to claim 14 wherein said alcohol is a straight
chain alcohol.
17. The process according to claim 14 wherein said alcohol is a branched
alcohol.
18. The process according to claim 15 wherein said alcohol is selected from
the group consisting of: methanol, ethanol, n-propanol, 2-propanol,
n-butanol, 2-butanol, and sec-butanol.
19. The process according to claim 1 wherein the amino compound contains at
least one hydrogen atom bonded to a nitrogen atom.
20. The process according to claim 1 wherein the amino compound is selected
from the group consisting of: ammonia, monoalkylamines, dialkylamines,
polyalkylene polyamines, alkylene polyamines, and amino acids.
21. The process according to claim 1 wherein said process is conducted in a
batch fashion.
22. The process according to claim 1 wherein said process is conducted in a
continuous fashion.
23. The process according to claim 22 wherein said process is conducted in
a tubular reactor.
24. The process of claim 1 wherein said contact includes mechanical mixing.
25. In a process for producing an alkanolamine by reaction of a polyolefin
epoxide with an amino compound by contacting a polyolefin epoxide with an
amino compound at an elevated temperature and pressure, wherein the
improvement comprises carrying out the reaction in the presence of a
catalytic amount of an alcohol.
26. A process according to claim 25 wherein the reactants are selected to
provide a nitrogen content in the alkanolamine product of between 0.03% by
weight and 20% by weight, including every hundredth percentage
therebetween.
27. A process according to claim 25 wherein the reactants are selected to
provide a nitrogen content in the alkanolamine product of between 0.20% by
weight and 3.0% by weight.
Description
This invention relates to a process for producing alkanolamines. More
particularly, the invention relates to a process for producing
alkanolamines from epoxides by admixture of an epoxide with an amino
compound having at least one hydrogen atom attached to a nitrogen atom in
the presence of a catalytic amount of an alcohol. Preferably, the epoxide
is derived from a polyolefin.
BACKGROUND
Alkanolamines have been known for decades and generally comprise an alcohol
function and an amino function as a part of the same organic molecule.
Some of the simplest alkanolamines include those known by those in the art
familiar with saponification, such as the ethanolamines: mono-, di-, and
tri-ethanol amines. The number of higher ethanolamines which are possible
is great, as the chain length of the hydrocarbon portion of a given
alkanolamine molecule can be varied from about 2 carbon atoms to upwards
of hundreds of carbon atoms in the case where the alkanolamine is derived
from a polymeric substrate. While it is to the higher alkanolamines to
which the present invention is primarily directed; the instant process is
applicable to production of the lower alkanolamines as well. However, the
benefits conferred through use of the invention are most pronounced in the
case of the production of alkanolamines having molecular weights in excess
of about 500.
Alkanolamines, or hydroxyalkyl amines as they are sometimes referred to,
are useful as additives for motor fuels, including, but not limited to
those motor fuels defined by ASTM specification D-439-73, as such amines
tend to reduce or eliminate unwanted deposits in the intake manifold,
runners, intake valve, and valve bowl area of a conventional automobile
engine. Examples of patents describing the use of such materials for this
purpose include the international patent application filed under the PCT
identifiable as international publication number WO 92/14806 of Ferro
Corporation, Cleveland, Ohio, USA, published Sep. 3, 1992, European Patent
Specification EP 0 516 838 B1 (International Publication number WO
92/12221), (Chevron Inc.), published Jul. 23, 1992, and European Patent
Specification EP 0 476 485 B1, (BASF) published Mar. 25, 1992, the entire
contents of all three of which references are herein incorporated by
reference thereto. The use of these materials as additives for motor fuels
is particularly attractive owing to the fact that they are halogen-free,
which means that organic halogen compounds are not formed as a result of
their combustion.
One synthetic route by which alkanolamines of high molecular weight may be
prepared is the multi-step process wherein a polyolefin is first converted
to an epoxide by means known to those skilled in the art. Such means may
be effected on any polyolefin, but the polyolefins polyethylene,
polypropylene, and polybutylene have been traditionally preferred.
Generally, an olefin homo- or co-polymer having a molecular weight in the
range of 170 to 5000, preferably 300 to 4000, more preferably 400 to 3500,
and most preferably 500 to 3000, is charged to a reactor along with an
effective amount of hydrogen peroxide, and especially preferably along
with a catalytic amount of a carboxylic acid, which catalyzes the
epoxidation of the olefin by presumably forming a peroxy acid as an
intermediate. The reaction is carried out at a temperature in the range of
about 60 to 85 degrees centigrade, and other conditions for such a
reaction is described in Organic Peroxides, Vol. 1, Wiley-Interscience,
New York, 1970, Daniel Swern at pages 340-369, inter alia, the entire
contents of which are herein incorporated by reference thereto, as well as
the patent publications already mentioned. Additionally, it has been found
by some workers to be convenient to employ a hydrocarbon solvent in which
to carry out the epoxidation. Typically, as is evident from the prior art
cited herein, several hours are required to effect a significant degree of
reaction between an epoxidized polyolefin and an amino compound, with
reaction times on the order of 10 to 16 hours being typical. Through use
of the instant invention, the reaction time may be reduced to only 2 to 3
hours. Reaction conditions are described in the prior art herein
incorporated by reference.
SUMMARY OF THE INVENTION
It has been unexpectedly discovered that the presence of a catalytic amount
of an alcohol greatly accelerates the rate of the reaction between the
epoxide and the amino compound in the formation of alkanols therefrom.
Accordingly, this invention is an alcohol-catalyzed process for forming an
alkanolamine from an epoxide and an amino compound which comprises
providing an epoxide and providing an amino compound, and preferably
mixing both in a reaction vessel capable of withstanding pressures on the
order of 3000 psig and 300 degrees centigrade which is also equipped with
a mechanical mixer. An effective catalytic amount of an alcohol is added
to the aforesaid mixture of amino compound and epoxide, and either the
temperature or pressure, or both are elevated sufficiently to cause a
reaction that results in the formation of an alkanolamine.
DETAILED DESCRIPTION
The present invention is a process for preparing alkanolamines by reacting
an epoxide, and especially a polyolefin epoxide, with an amino compound.
By their invention, the inventors hereof have discovered that the time
required for the reaction can be shortened significantly by having a
catalytic amount of an alcohol present. In order to form an alkanolamine
from an epoxide and an amino compound according to the invention, the
process includes charging of an epoxidized polymer to a reactor along with
an amino compound. The amino compound and the epoxidized polyolefin are
charged to a reactor and subjected to conditions of elevated temperature
and pressure which, although the inventors do not wish to be bound by any
particular theory, is believed to cause the epoxide ring to open, and
wherein the active hydrogen atom from a nitrogen atom is transferred to
the oxygen atom of the epoxide to form a nascent hydroxy group on the
polymer, and a carbon-nitrogen bond is formed between the nitrogen atom of
the amino compound and the carbon atom adjacent to the nascent hydroxy
group.
Any amino compound is suitable for the reaction, provided that the amino
compound contains at least one hydrogen attached to a nitrogen atom, and
that no other functional groups are present in the molecule which would
interfere substantially with the formation of the alkanolamine. Suitable
amines for the reaction are exemplified by, but not limited to, those
mentioned in the aforesaid patent publications, especially the preferred
amine compounds mentioned on the bottom of page 14 of PCT publication
92014806. For purposes of this specification and the appended claims the
words "amino compound" means ammonia or any organic compound comprising at
least one nitrogen atom, wherein the nitrogen atom has at least one
hydrogen atom bound thereto, regardless of the aromaticity, chain
branching, lack of chain branching, or presence of other known functional
groups present in the compound as a whole, including without limitation
those mentioned in PCT publication 92014806, and wherein there is at least
one nitrogen to carbon bond. It is readily recognized and appreciated by
those skilled in the organic chemical arts that included within this
definition are all organic mono- and polyamines. These include without
limitation ammonia, monoalkylamines, dialkylamines, polyalkylene
polyamines, alkylene polyamines, and amino acids. According to the
invention, amino compounds suitable for use herein may contain a
hydrocarbyl group that is straight-chain, branched, cyclic,
un-substituted, or substituted with various substituents known to those
skilled in the art as substituents in organic chemistry, with the proviso
that a substance, in order to qualify as an amino compound for purposes of
this specification and the appended claims must contain at least one
active hydrogen atom bonded to a nitrogen atom, and must not contain any
other substituents in the molecule which preclude formation of
alkanolamine. Suitable substituents include halogens, cyano groups, ester
groups, ether linkages, amido, etc. As used herein, the term "hydrocarbyl"
means a moiety comprising a carbon atom having at least one hydrogen atom
bonded to it, and includes alkyl groups, alkenyl groups, alkynly groups,
phenyl groups, benzyl groups aceto groups, as well as other
hydrocarbon-bearing species, whether such are straight chain, branched, or
cyclic, and saturated or unsaturated.
Exemplary but not delimitive of the class of monoalkylamines are:
methylamine, ethylamine, n-propylamine, butylamine, and other higher
analogues in this homologous series, (regardless of the presence or
absence of chain branching or substitution, i.e., compounds such as
2-aminopropane and 4-aminononane fall within this class) aniline,
phenethylamine etc. Exemplary but not delimitive of the class of
dialkylamines are diethylamine, dimethylamine, dipropylamine, and other
higher analogues in this homologous series including those either with or
without chain branching present. Dialkylamines by definition contain at
least two hydrocarbyl, (which are commonly alkyl) groups attached to a
nitrogen atom. It is believed to be well-known to those skilled in the
chemical arts that the two alkyl groups need not necessarily be the same,
but may differ. For example, there is a compound known as N-methyl,
N-ethyl amine which has both an ethyl and a methyl group bonded to a
nitrogen atom, in addition to an active hydrogen atom. Thus the present
invention contemplates the use of amino compounds having either the same
or different hydrocarbyl groups attached to the same nitrogen atom,
wherein one, both, or neither of such hydrocarbyl groups of the
dialkylamine include another nitrogen atom bonded to one of its carbon
atoms.
Polyalkylene polyamines are also useful in processes carried out in
accordance with the principles of this invention, and exemplary but not
delimitive of these materials are the amines which contain more than one
alkyl group, wherein the alkyl groups are joined together by a nitrogen
atom which may or may not have another substituent on the bridging
nitrogen atom, with the proviso, as is required of all amines useful in
accordance with this invention, that the molecule as a whole must contain
at least one nitrogen atom which has an active hydrogen atom bonded to it.
Such amines are well known in the art and are exemplified without
limitation by diethylene triamine, dipropylene triamine, dibutylene
triamine, triethylene tetramine, tripropylene tetramine, tetraethylene
pentamine, hexamethylene diamine, hexamethylenetetramine, etc., as members
of compounds of polyalkylene polyamines are known to those skilled in the
art.
The alkylene polyamines are organic amino compounds which comprise a carbon
chain having more than one nitrogen atom bonded to the carbon chain.
Exemplary of this class of compounds are 1,3 propanediamine, ethylene
diamine, butylamine diamines, etc., including those having at least one
other hydrocarbyl group attached to one or more of the nitrogen atoms.
Again, the main proviso is that the amino compound contain an active
hydrogen atom bonded to a nitrogen atom that is capable of undergoing
reaction with an epoxide to form an alkanolamine, as active hydrogen atoms
bonded to nitrogen atoms capable of participating in such reactions are
well-known to those skilled in the art. Such compounds are exemplified by
N,N-dimethylaminopropylamine, which is structurally an n-propyl amine
molecule which includes a dimethylamino group bonded to the gamma carbon
atom, which may also be termed 1-amino, 3-(N,N-dimethylamino) propane.
For purposes of this specification and the appended claims the word
"epoxide" means any epoxide, that is, an organic compound which contains
an oxirane ring, which ring is defined as a three-membered ring comprising
two carbon atoms and an oxygen atom. Such materials are well-known to be
formed from the reaction between a peroxide and an olefin. Exemplary
materials of this class are ethylene oxide, propylene oxide, and butylene
oxide. These materials are made industrially by the gas phase oxidation of
ethylene, propylene, and a butene, respectively. However, alternatively,
as already mentioned, olefinic bonds may be epoxidized by a peroxide. The
word epoxide includes all materials having an oxirane ring, regardless of
their molecular weight. However, the catalytic effect discovered by the
inventors hereof is pronounced in the case when the epoxide has a
molecular weight in excess of 170, more pronounced when the molecular
weight is in excess of 300, and most pronounced when the epoxide has a
molecular weight in excess of 500.
Suitable alcohols include any alcohol, straight chain, branched, or cyclic,
in which no appreciable amount of polyolefin epoxide is able to dissolve.
For purposes of this specification and the appended claims, the term
"straight-chain" means alcohols referred to by those of ordinary skill in
the art as normal alcohols, while "branched alcohols" are those which
possess even the smallest degree of what is well known to those skilled in
the art as "chain branching". All alcohols are either straight chain,
branched, or cyclic. A suitable alcohol for use in the invention is
cyclohexanol. Another preferred alcohol for purposes of this invention is
ethanol. The currently most preferred alcohol for this invention is
methanol.
An alcohol used as a catalyst according to the process of the invention
does not exert any solvent effect on the epoxidized polyolefin, but is
present, rather, in a catalytic amount. Alcohols are organic compounds
having a hydroxy group attached to a carbon atom, as is well-known to
those of ordinary skill in the chemical arts. For purposes of the instant
invention, the word alcohol means all such compounds generally recognized
as alcohols. The term also includes poly-ols, that is, organic molecules
having more than one hydroxy group per molecule. The process herein may be
operated in a batch process, or continuously. In a preferred form of the
invention, the alcohol catalyst used is not miscible with the polyolefin
epoxide employed as a reactant. For purposes of this invention and the
appended claims, the word "insoluble" means that the solute material is
soluble to less than 10 grams per liter in the solvent material.
It will be readily appreciated by those skilled in the art that materials
having various levels of nitrogen content, as expressed on a weight
percent basis, may be produced in accordance with the invention. This is
due to the versatility of the process in that a wide variety of possible
polyolefin epoxides may be reacted with a wide variety of possible amino
compounds. When a polyolefin epoxide having relatively low molecular
weight is reacted with an amino compound having a high percentage of
nitrogen, high levels of nitrogen in the finished product are encountered.
For example, when hexamethylene heptamine (M.W.=c.a.271) is reacted with a
polyolefin epoxide having a molecular weight of about 500, the resulting
product has a molecular weight of about 770, and is about 12.7% nitrogen.
Therefore, by judicious choice of reactants, one of ordinary skill after
reading this specification and claims may produce alkanolamines having
nitrogen contents between about 0.03% by weight and 20.0+%. Preferably,
when the products are to be used as additives for motor fuels, the
reactants are selected to provide a product having between about 0.10% and
10% nitrogen by weight, including every hundredth percentage therebetween.
More preferably, the nitrogen content is between 0.20% and 5.0%, and it is
most preferred that the nitrogen content be about 3.0% when the product is
to be admixed with gasoline for use as a motor fuel, to facilitate
blending. However, these ranges and percents should be viewed as exemplary
of the invention and not as delimitive thereof, as the artisan of ordinary
skill may readily determine the reactants necessary to provide a desired
nitrogen content in the finished product.
It is preferable to carry out reactions undertaken in accordance with this
invention at conditions of elevated temperature and pressure. For purposes
of this specification and the appended claims, the words "elevated
temperature and pressure" mean either a condition of elevated temperature,
or a condition of elevated pressure, or, as is most preferred, a
combination of the two. "Elevated" with respect to temperature means any
degree of temperature greater than 20 degrees centigrade. "Elevated" with
respect to pressure means any pressure greater than atmospheric pressure.
Conditions of elevated temperature may be used independently of one
another, or simultaneous, at any level or degree of either independent of
one another. Most preferably, the temperature is 200 degrees Centigrade,
and most preferably, the pressure is 1800 psig.
The following are examples of reactions conducted in accordance with the
invention and should be considered by all readers hereof as being merely
exemplary of the invention, and not delimitive of it in any way.
EXAMPLE I
A one-liter stirring autoclave is charged with 400 grams of a polyolefin
epoxide having a molecular weight of about 1000 and 24 grams of methanol.
The reactor is sealed from the atmosphere and purged with gaseous nitrogen
prior to charging with 150 grams of anhydrous ammonia. The reactor is
heated to a temperature of 200 degrees centigrade for three hours after
which time the reactor is cooled to ambient temperature and vented. The
resultant product is transferred to a flask and subsequently subjected to
reduced pressure, under moderate stirring, to remove traces of methanol
and ammonia in the mass. Following removal of such light-boiling
fractions, the product is analyzed and found to contain 0.56% nitrogen.
EXAMPLE II
Continuous Process
A 200 cc DOWTHERM.RTM. heated, stainless steel tubular upflow reactor which
has an inside diameter of 0.815" and a thermowell fabricated from 1/4-inch
0. D. tubing extended upward into the reactor and equipped with a baffle
is used. A polyolefin epoxide of molecular weight of about 1000 is fed at
a rate of 120 grams per hour through the tube along with a mixture of
ammonia and methanol (at a weight ratio of NH.sub.3 :MeOH of 9 to 1,
respectively) also fed at a rate of 120 grams per hour. The tube reactor
is maintained at a temperature of 220 degrees centigrade at a pressure of
2200 psig. The reactor effluent is stripped of ammonia, methanol, and
other light materials by means known to those in the art to produce a
material which contains 0.13% nitrogen.
EXAMPLE III
The procedure of Example II is followed except that the epoxide is fed at a
rate of 40 grams per hour and the mixture of ammonia to methanol had a
ratio of 3 to 2 and is fed at a rate of 50 grams per hour. The resulting
product contained 0.63% nitrogen.
EXAMPLE IV
The procedure of Example II is followed except that the epoxide is fed at
about 40 grams per hour and a mixture of ethylene diamine and methanol at
a weight ratio of 3 to 2 is fed at about 50 grams per hour. The reaction
is conducted at 230 degrees centigrade and 2000 psig. The reactor effluent
is dissolved in xylene and washed with water. Xylene and other lights are
removed under reduced pressure. The resulting product is analyzed to
contain about 1.81% nitrogen.
EXAMPLE V
The procedure of Example IV is followed, with the exception that
N,N-dimethyl aminopropylamine is used in the stead of ethylenediamine. The
lights are removed from the reactor effluent by distillation. The
resulting product is analyzed to contain about 1.65% nitrogen.
Although the present invention has been shown and described with respect to
certain preferred embodiments, it is obvious that equivalent alterations
and modifications will occur to others skilled in the art upon the reading
and understanding of the specification. The present invention includes all
such equivalent alterations and modifications, and is limited only by the
scope of the claims which now follow.
Top